High BMI is an indicator of abnormal HbA1c and the highest risk factor so far. This is an under diagnosed pathology in the US. Yes "fat" people are at very high risk.
There is not such thing as pre-diabetes, it is diabetes.
Many of these patients have underlying diseases such as diabetes. Diabetic patients have higher glycated hemoglobin. Glycated hemoglobin is a combination of hemoglobin and blood glucose, which is another reason of the high infection rate for older people.
COVID-19 Disease: ORF8 and Surface Glycoprotein Inhibit Heme Metabolism by Binding to Porphyrin
I'm not a medical doctor, however I have done substantial medical research on human metabolism (published). This is not medical advice but if I had elevated HbA1c and failed the Kraft glucose test, I would be taking 50mg of Zinc Picolinate a day. It may not help, however won't hurt. There is quite a library of literature on intercellular zinc issues with metabolic syndrome and type2 diabetes.
Best.